In general, the present invention relates to the field of communications, more particularly, to communication systems that provide communication services to wireless devices.
Communication systems that provide services or shared resources over wireless links are known. One such system is specified by Bluetooth that supports both asynchronous and isochronous services, where the services are offered to the wireless devices over point-to-point or point-to-multipoint communication links. Bluetooth technology allows for the replacement of the many proprietary cables that connect one device to another with one universal short-range radio link. For instance, Bluetooth radio technology built into both the cellular telephone and the laptop would replace the cumbersome cables used today to connect laptops to cellular telephones. Printers, PDA""s, desktops, fax machines, keyboards, and joysticks, for example, can be part of the Bluetooth system. But beyond untethering devices by replacing the cables, Bluetooth radio technology may provide a bridge to existing data networks, a peripheral interface, and a mechanism to form small private ad hoc groupings of connected devices away from fixed network infrastructures.
Under Bluetooth specification, a Service Discovery Protocol (SDP) defines the procedure for locating available services or shared resources, for example, printers. More specifically, SDP provides the means for client applications, which may be running on the wireless devices, to discover the existence of services or shared resources provided by server applications as well as the attributes of those services or resources. The attributes, of a service or resource, include the type or class of service offered and the mechanism or protocol information needed to utilize the service.
In order to provide point-to-point or point-to-multipoint communication links, Bluetooth uses a combination of circuit and packet switching. A point-to-point link is shared between only two Bluetooth-enabled wireless devices, whereas a point-to-multipoint link is shared among several wireless devices. Bluetooth can support one asynchronous data channel, up to three simultaneous synchronous voice channels, or a channel that simultaneously supports asynchronous data and synchronous voice.
Under the Bluetooth specification, two or more wireless devices that share the same channel form a piconet, and multiple piconets with overlapping coverage areas form a scatternet. One wireless device acts as the master device of the piconet, whereas the other wireless device(s) acts as slave device(s). Thus, each piconet can only have a single master device. However, slave devices can participate in different piconets on a time-division multiplex basis. In addition, a master device in one piconet can be a slave device in another piconet.
Communication resources of the Bluetooth system can support up to seven active slave devices in a piconet. Because Bluetooth system has a limited capacity to provide access to communication services over its supported links, the system allows some of the slave devices to remain locked to the master device in a so-called xe2x80x9cparkedxe2x80x9d state. The parked slave devices cannot be active on the channel, but remain synchronized to the master device. Both for active and parked slave devices, the channel access is controlled by the master device. Under this arrangement, once a communication resource of the system becomes available, a parked wireless device is activated to access a requested service. However, until activated, this arrangement deprives the parked wireless devices from enjoying the benefits of the provided services.
In the above mentioned conventional or known systems, the wireless devices access services or share resources without taking into consideration the surrounding context within which they are required to operate. Known computer systems for example allow users to boot in different modes depending on whether they are using a dialup connection or LAN. Also known is a pager that displays different news depending on its location. For example, such a system may not allow users to receive sports stories while they are at work.
When a large number of in-range devices communicate with each other on an ad-hoc basis, the system or devices that support such communication may become overwhelmed with allocating the resources required to communicate with the large number of devices. Thus, there exists a need for a system that allows for operating the wireless devices in a manner that optimally uses the available resources in accordance with an operating situation.